Problem: Express your answer as a mixed number simplified to lowest terms. $15\dfrac{17}{20}-7\dfrac{2}{8} = {?}$
Answer: Separate the whole numbers from the fractional parts: $= {15} + {\dfrac{17}{20}} - {7} - {\dfrac{2}{8}}$ Bring the whole numbers together and the fractions together: $= {15} - {7} + {\dfrac{17}{20}} - {\dfrac{2}{8}}$ Subtract the whole numbers: $=8 + {\dfrac{17}{20}} - {\dfrac{2}{8}}$ Simplify each fraction: $= 8 + {\dfrac{17}{20}} - {\dfrac{1}{4}}$ Find a common denominator for the fractions: $= 8+\dfrac{17}{20}-\dfrac{5}{20}$ Subtract the fractions: $= 8+\dfrac{12}{20}$ Combine the whole and fractional parts into a mixed number: $= 8\dfrac{12}{20}$ Simplify to lowest terms: $= 8\dfrac{3}{5}$